The use of wireless communication systems has achieved wide popularity in recent years as a result of advancements in communication technologies. Multi-user, wireless communication systems of improved capabilities are regularly utilized by large numbers of consumers to communicate both voice and non-voice information.
In a wireless communication system, a communication channel formed between a sending station and a receiving station is a radio channel defined upon a portion of the electromagnetic spectrum. Because a radio channel forms a communication link between the sending and receiving stations, a wireline connection is not required to be formed between the sending and receiving stations to permit the communication of data between the stations. Communication by way of a wireless communication system is thereby permitted at, and between, locations at which the formation of a conventional wireline connection would not be practical. Also, installation of the network infrastructure required of a radio communication system is generally more economically installed in contrast to a conventional wireline system as the infrastructure costs associated with a wireline communication system are significantly reduced.
A cellular communication system is exemplary of a wireless, multi-user radio communication system which has achieved wide levels of usage and which has been made possible due to advancements in communication technologies. A cellular communication system is typically formed of a plurality of fixed-site base stations installed throughout a geographical area and which are coupled to a public network, such as a PSTN (Public-Switched, Telephonic Network), or a packet data network, such as the Internet backbone. Portable transeivers, typically referred to as mobile stations, mobile terminals, or cellular phones, communicate with the base stations by way of radio links.
A cellular communication system efficiently utilizes the portion of the electromagnetic spectrum allocated thereto. Because of the spaced-apart positioning of the base stations, only relatively low-power signals are required to effectuate communications between a base station and a mobile station. As a result, the same frequencies can be reused at different locations throughout the geographical area. Thereby, communications can be effectuated between more than one set of sending and receiving stations concurrently at separate locations throughout the area encompassed by the cellular communication system.
In a cellular communication system, as in other types of radio communication systems, a transmitting station modulates data to be communicated to a receiving station upon a carrier wave of a carrier frequency within the range of frequencies which defines, at least in part, the communication channel. Through such a modulation process, a baseband level signal of which the data is formed is converted into a radio frequency signal of desired frequency characteristics.
A transmitting station, operable to transmit radio frequency signals upon a radio channel, typically includes one or more up-mixing stages at which the baseband information signal is up-converted in frequency of the selected radio frequency. The mixing stages include mixer circuits coupled to receive the information signal and an up-mixing signal with which the information signal is to be multiplied, or otherwise combined to form an up-converted signal. When multiple mixing stages are utilized, an IF (Intermediate Frequency) signal is formed at a first, or first series of, mixer stages. A radio frequency signal is formed at the final mixing stage.
A receiver which receives a radio-frequency communication signal transmitted thereto upon a radio communication channel must, analogously, convert the radio frequency signal to a baseband level. One or more down-conversion stages is utilized to down-convert the radio frequency signal to a baseband level.
Both the transmitting and receiving stations include, typically, one or more antenna transducers. The antenna transducer, when coupled to a transmitting station to form a portion thereof, transduces the radio frequency signal generated at the transmitter out of electrical form and into electromagnetic form for transmission upon the radio channel. The antenna transducer, when coupled to a receiving station to form a portion thereof, conversely, transduces radio frequency signals out of electromagnetic form and into electrical form for processing by circuitry of the receiving station.
A radio transceiver, having both a transmitting station and a receiving station to permit two-way communications, sometimes utilizes an antenna transducer which is shared by both the receiving and transmitting portions of the transceiver. A filter duplexer is sometimes utilized if the radio transceiver is operable pursuant to a frequency division multiplexing scheme having separate transmit and receive pass bands.
In a cellular communication system in which portable, mobile stations are utilized by a user to effectuate communications, size and performance considerations are significant factors which are determinative of the suitability of an antenna transducer to form a portion of a radio device. In a portable mobile station operable in a cellular communication system, for instance, size considerations are significant, particularly when the antenna transducer is to be housed within a housing of the mobile station. As the dimensions of the mobile stations increasingly become miniaturized, size considerations of the antenna transducer correspondingly become increasingly significant. And, the gain characteristics of the antenna transducer must be at least good enough to provide adequate pickup of signals transmitted to the mobile station and to facilitate transmission of communication signals generated at the mobile station therefrom.
Mobile stations constructed to provide positioning information of the location of the mobile station utilize GPS (global positioning system) signals generated by GPS satellites. The gain characteristics of the antenna transducer of the mobile station must be great enough to detect the satellite-generated GPS signals.
Any manner by which to facilitate improved antenna transducer performance while permitting the antenna transducer to be of reduced physical dimensions would be advantageous.
It is in light of this background information related to antenna apparatus that the significant improvements of the present invention have evolved.
The present invention, accordingly, advantageously provides an antenna assembly, and an associated method, for transducing radio frequency signals, such as the radio frequency signals generated by, or received at, a mobile station operable in a cellular, or other, radio communication system.
Through operation of an embodiment of the present invention, a manner is provided by which to form an antenna assembly of dimensions permitting its housing within the housing of the portable mobile station, or other radio device while also exhibiting improved gain characteristics compared to many conventional antenna transducers.
In one aspect of the present invention, an antenna assembly is provided for a mobile station operable in a cellular, or other radio, communication system. The antenna assembly is of dimensions to permit its positioning within the housing of the portable mobile station. And, the gain characteristics of the antenna transducer advantageously permit pickup of communication signals transmitted thereto during operation of the cellular, or other radio, communication system to permit subsequent processing of the signals at the mobile station.
In another aspect of the present invention, the antenna assembly includes an IFA (Inverted F-Antenna) transducer which exhibits circular polarization characteristics. In an exemplary implementation, the antenna transducer forms a TOPIFA (Top-Mounted Inverted F-Antenna) transducer. The TOPIFA is mounted at a printed circuit board at which radio circuitry of the mobile station is also formed. The IFA transducer is connected to a RF (Radio Frequency) port and a ground port formed on the printed circuit board. The IFA transducer extends along at least a portion of the width of the mobile station, within the housing, at a top portion of the mobile station, when operated, in typical manner by a user of the mobile station.
In another aspect of the present invention, the antenna assembly includes an antenna transducer element which is mounted upon a substrate, such as the aforementioned printed circuit board. The dimensions of the substrate are selected responsive to the frequencies at which the portable mobile station, or other radio device of which the antenna assembly forms a portion is operable. The widthwise and lengthwise dimensions of the substrate are selected such that a geometric mean of the widthwise dimension taken together with the lengthwise dimension of the substrate substantially corresponds to a resonance length defined by the frequencies within which the radio device is operable. Through such selection of the dimensions of the substrate, resonant currents are generated at the substrate. A first resonant current is generated in a capacitive direction of resonance, and a second resonant current is generated in an inductive direction of resonance. The capacitive and inductive directions of resonance are substantially perpendicular to each other and cause the antenna assembly to exhibit circular polarization characteristics.
In these and other aspects, therefore, an antenna transducer assembly, and an associated method, is provided for a radio device. The radio device includes radio circuitry having a RF (Radio Frequency) port and a ground port. A first antenna transducer element is coupled at a first portion thereof through the RF port of the radio circuitry. The first antenna transducer is coupled at a second portion thereof to the ground port of the radio circuitry. The RF port and the ground port are formed at a substrate. The substrate is of selected lengthwise and widthwise dimensions such that a capacitive resonance and an inductive resonance are formed of dissimilar phases. The dissimilar phases cause the first antenna transducer element to exhibit circular polarization when coupled to the RF port and to the ground port.
A more complete appreciation of the present invention and the scope thereof can be obtained from the accompanying drawings, which are briefly summarized below, the following detailed description of the presently-preferred embodiment of the invention, and the appended claims.